/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.qdxwx.captcha.filters.image;

import java.awt.*;
import java.util.Random;

/**
 * Some more useful math functions for image processing.
 * These are becoming obsolete as we move to Java2D. Use MiscComposite instead.
 */
public class PixelUtils {

	public final static int REPLACE = 0;
	public final static int NORMAL = 1;
	public final static int MIN = 2;
	public final static int MAX = 3;
	public final static int ADD = 4;
	public final static int SUBTRACT = 5;
	public final static int DIFFERENCE = 6;
	public final static int MULTIPLY = 7;
	public final static int HUE = 8;
	public final static int SATURATION = 9;
	public final static int VALUE = 10;
	public final static int COLOR = 11;
	public final static int SCREEN = 12;
	public final static int AVERAGE = 13;
	public final static int OVERLAY = 14;
	public final static int CLEAR = 15;
	public final static int EXCHANGE = 16;
	public final static int DISSOLVE = 17;
	public final static int DST_IN = 18;
	public final static int ALPHA = 19;
	public final static int ALPHA_TO_GRAY = 20;

	private static Random randomGenerator = new Random();

	/**
	 * Clamp a value to the range 0..255
	 */
	public static int clamp(int c) {
		if (c < 0)
			return 0;
		if (c > 255)
			return 255;
		return c;
	}

	public static int interpolate(int v1, int v2, float f) {
		return clamp((int)(v1+f*(v2-v1)));
	}
	
	public static int brightness(int rgb) {
		int r = (rgb >> 16) & 0xff;
		int g = (rgb >> 8) & 0xff;
		int b = rgb & 0xff;
		return (r+g+b)/3;
	}
	
	public static boolean nearColors(int rgb1, int rgb2, int tolerance) {
		int r1 = (rgb1 >> 16) & 0xff;
		int g1 = (rgb1 >> 8) & 0xff;
		int b1 = rgb1 & 0xff;
		int r2 = (rgb2 >> 16) & 0xff;
		int g2 = (rgb2 >> 8) & 0xff;
		int b2 = rgb2 & 0xff;
		return Math.abs(r1-r2) <= tolerance && Math.abs(g1-g2) <= tolerance && Math.abs(b1-b2) <= tolerance;
	}
	
	private final static float hsb1[] = new float[3];//FIXME-not thread safe
	private final static float hsb2[] = new float[3];//FIXME-not thread safe
	
	// Return rgb1 painted onto rgb2
	public static int combinePixels(int rgb1, int rgb2, int op) {
		return combinePixels(rgb1, rgb2, op, 0xff);
	}
	
	public static int combinePixels(int rgb1, int rgb2, int op, int extraAlpha, int channelMask) {
		return (rgb2 & ~channelMask) | combinePixels(rgb1 & channelMask, rgb2, op, extraAlpha);
	}
	
	public static int combinePixels(int rgb1, int rgb2, int op, int extraAlpha) {
		if (op == REPLACE)
			return rgb1;
		int a1 = (rgb1 >> 24) & 0xff;
		int r1 = (rgb1 >> 16) & 0xff;
		int g1 = (rgb1 >> 8) & 0xff;
		int b1 = rgb1 & 0xff;
		int a2 = (rgb2 >> 24) & 0xff;
		int r2 = (rgb2 >> 16) & 0xff;
		int g2 = (rgb2 >> 8) & 0xff;
		int b2 = rgb2 & 0xff;

		switch (op) {
		case NORMAL:
			break;
		case MIN:
			r1 = Math.min(r1, r2);
			g1 = Math.min(g1, g2);
			b1 = Math.min(b1, b2);
			break;
		case MAX:
			r1 = Math.max(r1, r2);
			g1 = Math.max(g1, g2);
			b1 = Math.max(b1, b2);
			break;
		case ADD:
			r1 = clamp(r1+r2);
			g1 = clamp(g1+g2);
			b1 = clamp(b1+b2);
			break;
		case SUBTRACT:
			r1 = clamp(r2-r1);
			g1 = clamp(g2-g1);
			b1 = clamp(b2-b1);
			break;
		case DIFFERENCE:
			r1 = clamp(Math.abs(r1-r2));
			g1 = clamp(Math.abs(g1-g2));
			b1 = clamp(Math.abs(b1-b2));
			break;
		case MULTIPLY:
			r1 = clamp(r1*r2/255);
			g1 = clamp(g1*g2/255);
			b1 = clamp(b1*b2/255);
			break;
		case DISSOLVE:
			if ((randomGenerator.nextInt() & 0xff) <= a1) {
				r1 = r2;
				g1 = g2;
				b1 = b2;
			}
			break;
		case AVERAGE:
			r1 = (r1+r2)/2;
			g1 = (g1+g2)/2;
			b1 = (b1+b2)/2;
			break;
		case HUE:
		case SATURATION:
		case VALUE:
		case COLOR:
			Color.RGBtoHSB(r1, g1, b1, hsb1);
			Color.RGBtoHSB(r2, g2, b2, hsb2);
			switch (op) {
			case HUE:
				hsb2[0] = hsb1[0];
				break;
			case SATURATION:
				hsb2[1] = hsb1[1];
				break;
			case VALUE:
				hsb2[2] = hsb1[2];
				break;
			case COLOR:
				hsb2[0] = hsb1[0];
				hsb2[1] = hsb1[1];
				break;
			}
			rgb1 = Color.HSBtoRGB(hsb2[0], hsb2[1], hsb2[2]);
			r1 = (rgb1 >> 16) & 0xff;
			g1 = (rgb1 >> 8) & 0xff;
			b1 = rgb1 & 0xff;
			break;
		case SCREEN:
			r1 = 255 - ((255 - r1) * (255 - r2)) / 255;
			g1 = 255 - ((255 - g1) * (255 - g2)) / 255;
			b1 = 255 - ((255 - b1) * (255 - b2)) / 255;
			break;
		case OVERLAY:
			int m, s;
			s = 255 - ((255 - r1) * (255 - r2)) / 255;
			m = r1 * r2 / 255;
			r1 = (s * r1 + m * (255 - r1)) / 255;
			s = 255 - ((255 - g1) * (255 - g2)) / 255;
			m = g1 * g2 / 255;
			g1 = (s * g1 + m * (255 - g1)) / 255;
			s = 255 - ((255 - b1) * (255 - b2)) / 255;
			m = b1 * b2 / 255;
			b1 = (s * b1 + m * (255 - b1)) / 255;
			break;
		case CLEAR:
			r1 = g1 = b1 = 0xff;
			break;
		case DST_IN:
			r1 = clamp((r2*a1)/255);
			g1 = clamp((g2*a1)/255);
			b1 = clamp((b2*a1)/255);
			a1 = clamp((a2*a1)/255);
			return (a1 << 24) | (r1 << 16) | (g1 << 8) | b1;
		case ALPHA:
			a1 = a1*a2/255;
			return (a1 << 24) | (r2 << 16) | (g2 << 8) | b2;
		case ALPHA_TO_GRAY:
			int na = 255-a1;
			return (a1 << 24) | (na << 16) | (na << 8) | na;
		}
		if (extraAlpha != 0xff || a1 != 0xff) {
			a1 = a1*extraAlpha/255;
			int a3 = (255-a1)*a2/255;
			r1 = clamp((r1*a1+r2*a3)/255);
			g1 = clamp((g1*a1+g2*a3)/255);
			b1 = clamp((b1*a1+b2*a3)/255);
			a1 = clamp(a1+a3);
		}
		return (a1 << 24) | (r1 << 16) | (g1 << 8) | b1;
	}

}
